SURVEYING

1. SURVEYING Department of Civil Engineering Lecturer Dr. Farag Bastawy Farag drfarag7@yahoo.com dr.farag.7@hotmail.com Lecture of Surveying and Geodesy Surveying Department Shoubra Faculty of Engineering

2. 4. Obstacles 1

3. Obstruction to ranging only. Obstruction to measuring only Obstruction To measuring & ranging Obstruction can be Measured around Obstruction can not be measured around

4. 1) Obstructions to ranging only On hilly ground very often, due to undulations of some size, the last station point cannot be seen from the first, yet intermediate poles must be positioned for lining in the chainmen. The difficulty may be resolved by tying two poles together, although this is not very accurate or satisfactory. In Fig A and B are the two stations seen in the plane, with the hill between them (as shown by the section). Two assistants with poles take up positions, one on each side of the hill, at C1 and D1 and facing each other so that the observer at C1 can see the pole at station A and observer at D1 can see the pole at station B. By successively directing each other into line, their positions will be altered until finally they finish at C and B exactly on the line AB and then poles are inserted

7. 2) Obstructions to measuring only When the obstructions cannot be measured as like this type of lands. Lakes, ponds, marsh and railway cross. That time we must handle these methods to get measurements. a) At the marsh or ponds (Rectangle method)

8. b)1- At the marsh or ponds (Triangles method) b)2- At the railway crosses or rivers

9. 3) Obstructions to both measuring and ranging This type of measurements is done for highest lands As like mountains, buildings and forest. Line FI and line AB are parallel to each one. The figure shows a typical situation, where Survey line is interrupted. Therefore, FI//A B, Then EH =HD Therefore EHDC is a square. AB= AC+EH+DB

10. THANKS